Gas turbine engine assembly and methods of assembling same

ABSTRACT

A turbine engine assembly includes, a core gas turbine engine, a first low-pressure turbine section in serial flow communication with the core gas turbine engine, the first low-pressure turbine section configured to rotate in a first rotational direction, a first gear assembly coupled to the first low-pressure turbine section, a second low-pressure turbine section coupled to the gear assembly, the second low-pressure turbine section configured to rotate in a second rotational direction, and a fan assembly coupled to the second low-pressure turbine section.

BACKGROUND OF THE INVENTION

This invention relates generally to gas turbine engines, and more specifically to gas turbine engine assemblies and methods of assembling the same.

At least some known gas turbine engines include a fan, a core engine, and a power turbine. The core engine includes at least one compressor, a combustor, a high-pressure turbine and a low-pressure turbine coupled together in a serial flow relationship. More specifically, the compressor and high-pressure turbine are coupled through a shaft to define a high-pressure rotor assembly. Air entering the core engine is mixed with fuel and ignited to form a high energy gas stream. The high energy gas stream flows through the high-pressure turbine to rotatably drive the high-pressure turbine such that the shaft, in turn, rotatably drives the compressor.

The gas stream expands as it flows through the low-pressure turbine positioned aft of the high-pressure turbine. The low-pressure turbine includes a rotor assembly having a fan coupled to a drive shaft. The low-pressure turbine rotatably drives the fan through the drive shaft.

Modern commercial turbofans tend toward higher bypass ratios to improve efficiency. For acoustic and fan efficiency reasons, it is desirable to reduce fan RPM or tip speed. However, a lower RPM increases low-pressure turbine loading, diameter and/or stage count. A fan directly driven by the low-pressure turbine limits the choice in fan speed because a slight reduction in fan speed for improved performance results in poorer performance in the low-pressure turbine.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a turbine engine assembly including, a core gas turbine engine, a first low-pressure turbine section in serial flow communication with the core gas turbine engine, the first low-pressure turbine section configured to rotate in a first rotational direction, a first gear assembly coupled to the first low-pressure turbine section, a second low-pressure turbine section coupled to the gear assembly, the second low-pressure turbine section configured to rotate in a second rotational direction, and a fan assembly coupled to the second low-pressure turbine section.

In another aspect, a method for assembling a gas turbine engine including, coupling a first section of a low pressure turbine downstream of a core gas turbine engine, wherein the first section of the low pressure turbine rotates in a first direction, coupling a first gear assembly to the first stage of the low pressure turbine, coupling a second section of the low pressure turbine to the first gear assembly, wherein the second section of the low pressure turbine rotates in a second direction, and coupling a single stage fan assembly to the second section of the low pressure turbine.

In a further aspect, a gas turbine engine assembly including, a core gas turbine engine, a first low-pressure turbine section in serial flow communication with the core gas turbine engine, a second low-pressure turbine section in serial flow communication with the core gas turbine engine aft of the first low-pressure turbine section, a fan assembly coupled to the second low-pressure turbine section, a booster compressor coupled to the first low-pressure turbine section, and a gear assembly coupled between said booster compressor and said fan assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 show exemplary embodiments of the assembly and method described herein.

FIG. 1 is a cross-sectional view of an exemplary turbine engine assembly;

FIG. 2 is a simplified representation of one embodiment of a turbine engine assembly in accordance with the present invention;

FIG. 3 is a simplified representation of one embodiment of a turbine engine assembly in accordance with the present invention; and

FIG. 4 is a simplified representation of an additional embodiment of a turbine engine assembly in accordance with the present invention; and

FIG. 5 is a simplified representation of an additional embodiment of a turbine engine assembly in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a cross-sectional view of a portion of an exemplary turbine engine assembly 10 having a longitudinal axis 11. In the exemplary embodiment, turbine engine assembly 10 includes a core gas turbine engine 12 generally defined by a casing 13. A low-pressure turbine 14 is coupled axially aft of core gas turbine engine 12 and a single-stage fan assembly 16 is coupled axially forward of core gas turbine engine 12.

Core gas turbine engine 12 includes an outer casing 20 that defines an annular core engine inlet 22. Casing 20 surrounds a low-pressure booster compressor 24. Single-stage fan assembly 16 increases the pressure of incoming air to a first pressure level and directs a portion of the incoming air to the low-pressure booster compressor 24. Low-pressure booster compressor 24 receives air from the single-stage fan assembly 16 and facilitates increasing the pressure to a higher, second pressure level. In one embodiment, core gas turbine engine 12 is a core CFM56 gas turbine engine available from General Electric Aircraft Engines, Cincinnati, Ohio. In another embodiment a high pressure core is used and the booster is not.

In some embodiments, a high-pressure, multi-stage, axial-flow compressor 26 receives pressurized air from booster compressor 24 and further increases the pressure of the air to a third, higher pressure level. The high-pressure air is channeled to a combustor 28 and is mixed with fuel. The fuel-air mixture is ignited to raise the temperature and energy level of the pressurized air. The high energy combustion products flow to a first or high-pressure turbine 30 for driving compressor 26 through a first rotatable drive shaft 32, and then to second or low-pressure turbine 14. After driving low-pressure turbine 14, the combustion products leave turbine engine assembly 10 through an exhaust nozzle (not shown) to provide propulsive jet thrust.

In one embodiment, booster compressor 24 includes a plurality of rows of rotor blades 70 that are coupled to a respective rotor disk 72. Booster compressor 24 is positioned aft of an inlet guide vane assembly 74 and is coupled to a drive shaft 34 such that booster compressor 24 rotates at a rotational speed that is substantially equal to a rotational speed of fan assembly 16. Although booster compressor 24 is shown as having only three rows of rotor blades 70, booster compressor 24 may have any suitable number and/or rows of rotor blades 70, such as a single row of rotor blades 70 or a plurality of rows of rotor blades 70 that are interdigitated with a plurality of rows of guide vanes 76. In one embodiment, guide vanes 76 are fixedly or securely coupled to a booster case 78. In an alternative embodiment, rotor blades 70 are rotatably coupled to rotor disk 72 such that guide vanes 76 are movable during engine operation to facilitate varying a quantity of air channeled through booster compressor 24. In another alternative embodiment, turbine engine assembly 10 does not include booster compressor 24.

Low-pressure turbine 14 includes two sections, a first section 80 and a second section 82. Although first section 80 is shown with one stage and second section 82 is shown with two stages each section may have multiple or single stages in other embodiments. First section 80 is coupled to a first intermediate drive shaft 84 and rotates in a first direction with a first rotational speed while second section 82 is coupled to a second intermediate drive shaft 86 and rotates in a second direction with a second rotational speed. Both first and second intermediate drive shafts 84 and 86 are coupled to second rotatable drive shaft 34 through a gear assembly 88. In the exemplary embodiment gear assembly 88 is a planetary (star type) reversing and speed reducing gear assembly. In other embodiments, gear assembly 88 may be any other type of gear assembly.

Second rotatable drive shaft 34 drives fan assembly 16. Fan assembly 16 is configured to rotate about longitudinal axis 11 in a second rotational direction, includes at least one row of rotor blades 60, and is positioned within a fan case 64. Rotor blades 60 are coupled to a rotor disk 66.

FIG. 2 describes one embodiment of the claimed invention. In the exemplary embodiment, gas turbine engine 100 includes a compressor 102, a core gas engine 104, a high pressure turbine 110 and a low-pressure turbine 114 in serial flow arrangement. High pressure turbine 110 drives compressor 102 through a first rotatable shaft 112. Low pressure turbine 114 includes two sections, a first section 116 and a second section 118. Although not shown, the first section 116 and the second section 118 may have multiple or single stages in various embodiments. First section 116 is coupled to a first intermediate drive shaft (not shown) and rotates in a first direction with a first rotational speed while second section 118 is coupled to a second intermediate drive shaft (not shown) and rotates in a second direction with a second rotational speed. Both first and second intermediate drive shafts (not shown) are coupled to second rotatable drive shaft 120 through a gear assembly 122. Second rotatable drive shaft 120 drives a fan assembly 124 and a low-pressure booster compressor 126. Fan assembly 124 is configured to rotate about longitudinal axis 111 in a second rotational direction.

FIG. 3 describes another embodiment where a low pressure turbine 314 is divided into a first section 316 and a second section 318. First section 316 and second section 318 are coupled to a second rotatable drive shaft 320 through a first gear assembly 322. Second rotatable drive shaft 320 is coupled to and directly drives fan assembly 324. Second rotatable drive shaft 320 also drives the booster 326 through a second gear assembly 328.

FIG. 4 describes still another embodiment where a low pressure turbine 414 is divided into a first section 416 and a second section 418. First section 416 couples directly to a second rotatable drive shaft 420 that directly drives a booster compressor 424 and drives a fan assembly 426 through a gear assembly 428. Second section 418 couples directly to a third rotatable drive shaft 430 that couples directly to and drives fan assembly 416.

FIG. 5 describes still another embodiment where a high pressure core engine 508 is coupled to a high pressure turbine 510 through a first rotatable drive shaft 512. Low pressure turbine 514 is located axially aft of the high pressure turbine 510 and is divided into a first section 516 and a second section 518. First section 516 and second section 518 are coupled to a second rotatable drive shaft 520 through a first gear assembly 522. Second rotatable drive shaft 520 is coupled to and directly drives fan assembly 524.

Exemplary embodiments of a gas turbine engine assembly and methods of assembly the gas turbine engine assembly are described above in detail. The assembly and method are not limited to the specific embodiments described herein, but rather, components of the assembly and/or steps of the method may be utilized independently and separately from other components and/or steps described herein. Further, the described assembly components and/or the method steps can also be defined in, or used in combination with, other assemblies and/or methods, and are not limited to practice with only the assembly and/or method as described herein.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

1. A turbine engine assembly comprising; a core gas turbine engine; a first low-pressure turbine section in serial flow communication with said core gas turbine engine, said first low-pressure turbine section configured to rotate in a first rotational direction; a first gear assembly coupled to said first low-pressure turbine section; a second low-pressure turbine section coupled to said gear assembly, said second low-pressure turbine section configured to rotate in a second rotational direction; and a fan assembly coupled to said second low-pressure turbine section.
 2. A turbine engine assembly in accordance with claim 1 further comprising a booster compressor coupled to said second low-pressure turbine section.
 3. A turbine engine assembly in accordance with claim 1 wherein said core gas turbine engine comprises a high pressure core.
 4. A turbine engine assembly in accordance with claim 2 further comprising a second gear assembly coupled between said booster compressor and said second low-pressure turbine section.
 5. A turbine engine assembly in accordance with claim 2 wherein said booster compressor is configured to rotate in the second direction.
 6. A turbine engine assembly in accordance with claim 1 wherein said fan assembly comprises a single stage fan.
 7. A turbine engine assembly in accordance with claim 1 wherein said first direction is opposite said second direction.
 8. A turbine engine assembly in accordance with claim 1 wherein said fan assembly is configured to rotate in said second rotational direction.
 9. A method for assembling a gas turbine engine, the method comprising: coupling a first section of a low pressure turbine downstream of a core gas turbine engine, wherein the first section of the low pressure turbine rotates in a first direction; coupling a first gear assembly to the first section of the low pressure turbine; coupling a second section of the low pressure turbine to the first gear assembly, wherein the second section of the low pressure turbine rotates in a second direction; and coupling a single stage fan assembly to the second section of the low pressure turbine.
 10. A method in accordance with claim 9 further comprising: coupling a second gear assembly to said fan assembly; and coupling a booster compressor to the second gear assembly.
 11. A method in accordance with claim 9 further comprising coupling a booster compressor to the second section of the low-pressure turbine.
 12. A method in accordance with claim 9 wherein coupling a first stage of a low pressure turbine to a core turbine engine further comprises coupling a first stage of a low pressure turbine to a high pressure ratio core turbine engine.
 13. A method in accordance with claim 9 wherein coupling a single stage fan assembly to the second section of the low pressure turbine engine further comprises coupling a single stage fan assembly configured to rotate in a second direction to the second section of the low pressure turbine engine.
 14. A method in accordance with claim 11 wherein coupling a booster compressor to the second section of the low-pressure turbine further comprises coupling the booster compressor configured to rotate in the second direction to the second section of the low-pressure turbine.
 15. A gas turbine engine assembly comprising: a core gas turbine engine; a first low-pressure turbine section in serial flow communication with said core gas turbine engine; a second low-pressure turbine section in serial flow communication with said core gas turbine engine aft of said first low-pressure turbine section; a fan assembly coupled to said second low-pressure turbine section; a booster compressor coupled to said first low-pressure turbine section; and a gear assembly coupled between said booster compressor and said fan assembly.
 16. A gas turbine engine assembly in accordance with claim 15 wherein said booster compressor rotates in a first direction and said second low-pressure turbine section rotates in a second direction, opposite the first direction.
 17. A gas turbine engine assembly in accordance with claim 15 wherein said booster compressor is coupled to said first low-pressure turbine section via a first drive shaft and said fan assembly is coupled to said second low-pressure turbine section via a second drive shaft.
 18. A gas turbine engine assembly in accordance with claim 15 wherein said booster compressor rotates at a first rotational speed and said second low pressure turbine section rotates at a second rotational speed, wherein the first rotational speed is substantially faster than the second rotational speed.
 19. A gas turbine engine assembly in accordance with claim 15 wherein said fan assembly comprises a single stage fan assembly. 